The thing I adore about The Jerk is that, towards the end of the episode, House tells Foreman he's "not ready" to leave. He does this, of course, because he can't admit the larger truth (that he wants Foreman to stay), but the thing is, House is also correct.
HOUSE: You're not ready.
HOUSE: There was a third choice. Don't do what I asked. You coulda defied me, stuck the kid on antibiotics. But you didn't. Because you still trust my judgment more than your own.
This is actually a running theme -- and fault -- of Foreman's. He talks big game, but he has a massive insecure streak, and he tends to founder and hesitate when he's put in charge (DNR, but also his S2 leadership arc), he does trust House's judgement. This will come up again in S5 (Emancipation), which is also when Foreman finally stops deferring to House, but it's a huge part of his character.
But House is right in another way, too.
In The Jerk, in an early scene, Foreman is examining the patient, who complains he can't bend his fingers. Foreman is annoyed by the guy and shrugs it off. This turns out to be the Big Clue of the episode, the thing House uses to solve the case: Foreman missed it.
But here's the other thing.
In Resignation, Foreman announces he's leaving. Chase is curious about this, and does some poking. Both Foreman and House tell him he's wrong and to drop it, but Chase is certain he's right -- and he is. In the same episode, he has a theory about the patient. He's wrong, but so is House; they argue about it and Chase refuses to back down. He gets the test he'd wanted: his diagnosis is wrong but he points out that the result wasn't what House expected, that House is wrong too.
This isn't something we've really gotten from Chase before. Foreman and Cameron argue with House plenty, but Chase usually shrugs and goes along. But it's something that happens repeatedly in S3, after Finding Judas: Chase pushes his theories in Insensitive and Words and Deeds; he solves a case in Airborne, he pokes at Foreman and House in Resignation and The Jerk.
Chase to Wilson in Finding Judas: "I'm not waiting [for House's approval] anymore."
House to Chase in The Jerk, after Chase correctly calls him out for a scheme: "Sometimes I forget why I hired you."
Chase is ready to move on. Chase trusts his own judgement now and going forward, doesn't rely on House's approval -- or necessarily believe House just because House insists he's right.
But Foreman isn't there yet, even though he wants to be. He's leaving because he's afraid of House, afraid of being House's favorite and what that means. He isn't truly confident yet, he isn't ready. He missed the Big Clue. In the same episode, Chase uncovers a (completely different) mystery. One of them is ready, and it isn't Foreman.